MPs were today staging an emergency debate on the decision to deploy a 1,700-strong Royal Marine battle group to Afghanistan to root out the remaining al Qaida and Taliban fighters.

MPs were today staging an emergency debate on the decision to deploy a 1,700-strong Royal Marine battle group to Afghanistan to root out the remaining al Qaida and Taliban fighters.

It follows the decision yesterday by Commons Speaker Michael Martin to take the unusual step of granting the Conservatives an emergency debate before MPs break next week for their Easter recess.

Shadow defence secretary Bernard Jenkin said while the Tories backed the decision to send the marines of 45 Commando to support the Americans, the announcement had come as a surprise and should be fully debated by MPs.

There were signs of misgivings among some Labour MPs over the deployment - the largest British war force to be sent overseas since the 1991 Gulf conflict.

Many backbenchers were already concerned at Tony Blair's expressions of support for possible military action by the US to extend the war against terrorism to Iraq.

The lead elements of 45 Commando were expected to begin arriving at Bagram airbase, near the capital Kabul, over the next couple of days, ready to begin operations next month.

The marines could face thousands of Taliban holed up in the country's rugged countryside, defence experts warned today.

Major Charles Heyman, editor of Jane's World Armies, said that as many as 10,000 Taliban fighters could still be active in southern and south-eastern Afghanistan.

Meanwhile, gunmen attacked US and Afghan troops in eastern Afghanistan last night, sparking a battle that lasted several hours, a US military spokesman said today.